A number of synchrotron radiation-based X-ray characterization tools are used for both chemical and physical characterization of materials, especially in a liquid environment. Among these, X-ray absorption spectroscopy (XAS) is a versatile tool to probe oxidation states, coordination, and local order of materials, even in the absence of a crystalline lattice. XAS has been used to investigate the electronic and geometric structures of nanomaterials; more specifically, to map local coordination number, the extent of alloying and composition of multi-metallic systems in solution. Further, in situ XAS offers an opportunity to observe time-resolved bond formation, changes in oxidation states, coordination, and local order. The ability to follow the fundamental processes in the synthesis of nano structured materials with atomic precision is an unfulfilled need in the field of nanoscience.
Microfluidic systems have been used to prepare a wide range of materials. These systems consist of small channels of micrometer dimensions in which the reactive liquid precursors needed to produce solid clusters of metals are mixed and allowed to react. Recently, they have become an attractive technology due to their ability to rapidly mix reagents, provide homogeneous reaction environments, continuously vary reaction conditions, add reagents at precise time intervals during reaction, and the ability to control the residence time by varying the reactant flow-rates and/or the length of the flow channel. These features have been cleverly utilized in the wet-chemical synthesis of nanomaterials not only to control their size, size-distribution, and shape, but also to control their crystal structure and for faster clinical translation.
The use of XAS in conjunction with microfluidic systems provides a powerful new method for in situ time-resolved experiments probing the structure and reaction dynamics at atomic level. However, a major drawback of microfluidic chips is the inability to obtain high quality data from techniques such as in situ XAS for sample concentration in excess of 0.1 M. Thus, new techniques and devices are needed to overcome these drawbacks.
Additionally, there are problems in coating fluidic channels with catalysts having controlled dimensions and morphology. A catalyst coating having controlled dimensions and morphology is important for carrying out chemical reactions and characterization of the same while also preventing channel clogging. Controlled morphology of the catalyst is required for better catalysis and also for continuous flow synthesis. Accordingly, there is a need for methods for coating fluidic channels with catalysts having controlled dimensions and morphology, particularly where the coating avoids or prevents channel clogging.
Further, there is a need for hand-held and user friendly devices for coating channels with catalyst and other structures having controlled dimensions and morphology, and for carrying out processes such as chemical and biological reactions, characterization, continuous flow cell culturing, enzymatic catalysis, biomolecular catalysis, reactions involving homogeneous catalysts bound to channel walls, peptide synthesis, nucleic acid synthesis, synthesis of pharmaceutical intermediates, biofunctionalization of nanomaterials, combinatorial chemistry, and others.